I have a 1991 Olds Regency (non-supercharged)...... when the engine is cold it stumbles..... I have replaced the plugs, wires,coil pack, ICM, ICM wiring harness, Temp Sensor, Cam Sensor, Crank Sensor.......what else could cause the stumble.....after engine warms after about 10 minutes seems to be ok.......................

Possible manifold leak that seals when warm.

Possible faulty Idle Air Control.

I agree with both above ^^^^^^^

I tend to lean towards the vacuum leak a little more than the IAC, but the IAC is easier to check.